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(No' Model.) v p 1 0,13. SGRIBNER, MULTIPLE SWITOHBOARD'KEYBOARDAPPARATUS,

No. 504,249. Patented Aug. 29,1893.

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I f 1 i G UNITE TATES VATEN'I OFFICE.

CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WESTERNELECTRIC COMPANY, OF SAME PLACE.

' M U LTI PLE SWITCH BOARD KEYBOARD APPARATU S.

SPECIFICATION forming part of Letters Patent-No. 504,249, dated August29, 1 893.

Application filed December 6, 1887. Renewal December 13, 1892. SerialNo. 455,011. (No model.)

To all whom it may concern.-

Be it known that I, CHARLES E. SORIBNER, a citizen of the United States,residing at Chicago, 1n the county of Cook and State of Illinois, haveinvented a certain new and useful Improvement in Multiple SwitchboardKeyboard Apparatus, (Case No. 145,) of which the following is a full,clear,concise, and exact description, reference being had to the accomropanying drawings, forming a part of this specification.

My invention relates to the flexible cords and terminal plugs of asingle cord multiple switchboard system, and its object is to afford r 5a ready means of closing a telephone through the operators telephoneline when a plug is lifted and the normal ground removed. The plug isprovided with a metallic shank which is insulated from the extreme tip,the extreme tip and shank being connected with different strands of aflexible cord, one strand leading to the line and the other to theoperators telephone line. On lifting the plug and closing the connectionbetween the ex- 2 5 treme tip and the metallic shank, the line is atonce connected with the operators telephone. I preferably provide aflexible metallic tinsel piece in the form of a cot upon the finger ofthe operator which the operator presses against the plug point so as tobridge over the insulation between the extreme tip and the shank.Instead of tinsel the operator may insert the tip of the plug in mercuryor make the connection in other'suitable 3 5 manner.

My invention is illustrated in the accompanying drawings, in which-Figure 1 is a diagram illustrative of sections of two multipleswitchboards and two telephone lines connected therewith according tothe single cord system, the test wires being also shown connected in theusual manner. Fig. 2 is a detailed sectional view of the plug.

5 The circuit of telephone line a may be traced normally throughspring-jack 1) upon the first board and spring-jack 0 upon the secondboard through the individual annunciator d and thence by wire e toswitch f and thence by strand 9 of the flexible cord to the shank ofplug h, the shank of plug h being in electrical connection with the heelpiece of the plug. The heel piece normally rests upon ground contactspring 41, thus closat board 2, is connected with strand t of theflexible cord, this strand t leading to the extreme tip of the plug. Theoperator at board 2 on seeing the shutter of line a fall, at once picksup the plug of line a, thus lifting the heel of said plug from theground plate and taking off the normal ground connection of the line. Atthe same time he lifts the plug. He also by means of the tinsel 14 uponhis finger bridges over the insulation between the tip and the shank.Thus the line 0!, is connected with the telephone 2;. The circuit thusclosed may be traced byline a, through the spring-jacks b c andannunciator d and wire 6 to spring f and thence by strand g to the shankof plug it and thence by tinsel u to the extreme tip of the plug whichis connected with strand t of the flexible cord and thence through thetelephone 1; to ground. The op erator thus, as he lifts the plug, may,by the same hand and at the same time, close the circuit of the linethrough his telephone. Upon receiving the order he uses, preferably, thesame plug to make the usual test, and if he finds the line wanted free,he at once inserts his plug it therein and by means of a key 20 or inany other suitable manner, throws current to line to call the desiredsubscriber. Having thus described my invention, I claim as new anddesire to secure by Letters Patent-- l. A telephone line connected withone point of a terminal plug and a telephone connected with anotherpoint of the same plug,

and a connecting device for closing the oirtip and the shank at the willof the operator,

ouit between the two points of the plug to as described. to connect saidline with the telephone, sub- In witness whereof I hereunto subscribe mystantially as described. name this 17th day of October, A. D. 1887.

5 2. Aplug provided with an insulated shank CHARLES E. SORIBNER.

and an insulated tip and a yielding metallic Witnesses: fabric adaptedto be worn upon the finger so WM. M. CARPENTER,

as to readily close the connection between the CHAS. O. WOODWORTH.

